The present invention relates to general displacement and/or strain sensors, and in particular, to a displacement and/or strain sensor assembly/package comprised of a displacement or strain sensor bonded to an anisotropic mounting substrate for providing a strong response to axial displacements and forces along a single axis.
Displacement and/or strain sensors are utilized in a wide variety of applications, including defense, industrial, and commercial applications. These applications often require very sensitive, rugged, and reliable displacement and/or strain sensors, to provide enhanced performance, overload protection, and/or health and safety monitoring. For example, displacement and/or strain sensors are utilized to monitor strain in continuous sections and displacement across joints and air gaps in aircraft, bridges, dams, tunnels, monuments, buildings, elevators, presses, machine tools, cranes, aerial platforms, agricultural machines, and machinery. Displacement and/or strain sensors may further be utilized in a variety of load-sensing applications, such as weighing of vehicles or vessels and the contents of silos and storage tanks, as well as for enhanced performance and process control, overload protection, and health monitoring.
When a displacement and/or strain sensor is operatively mounted for use in an application, care must be taken to ensure that the strain sensor is properly aligned with the axis along which the desired displacements and/or strains are to be measured, and that the displacement and/or strain sensor is isolated from off-axis displacements and/or strains which might alter the displacements and/or strains measurements along the desired axis, introducing errors.
Traditionally, displacement and/or strain sensor assemblies are a compromise between measurement sensitivity and package durability. Sensors possessing a high degree of sensitivity are often not sufficiently durable for use in demanding applications. As package durability is increased, many defense, industrial, and commercial applications could rely on very sensitive, rugged, reliable displacement/strain sensors to provide enhanced performance, overload protection, and/or health/safety monitoring. Some exemplary applications for such a displacement and/or strain sensor include the following:
Monitoring strain in continuous sections of structures and displacement across joints and air gaps in aircraft, bridges, dams, tunnels, monuments, buildings, elevators, presses, machine tools, cranes, aerial platforms, agricultural machines, machinery, etc.;
Weighing vessels, silos, storage tanks, and other load sensing applications;
Research and development projects which require measurement of strain and/or displacement; and
Measuring load for enhanced performance and process control, overload protection, and health monitoring.
Accordingly, it would be advantageous to provide a displacement and/or strain sensor assembly having an anisotropic stiffness to facilitate the measurement of displacements in one desired direction, while minimizing errors due to undesired displacements and rotations. It would be further advantageous to provide the displacement and/or strain sensor assembly with a packaged design which is configured to include a temperature sensor to compensate the displacement and/or strain sensor for thermal effects, provide temperature information to an end user, and which is configured for easy attachment/detachment to application structures. Additionally, it would be advantageous to provide an improved displacement and/or strain sensor assembly which has a high degree of sensitivity, and which is disposed in a durable package to withstand a variety of operating environments and conditions.